Filmmaker Errol Morris has focused his lens on two defense secretaries, a man wrongly convicted of murder and Stephen Hawking. So when the Oscar winner told his friend Elsa Dorfman he wanted to make a documentary about her, the idiosyncratic photographer tells the Post she “blew him off.”

“I said OK — anything to shut him up,” says the 80-year-old Dorfman, who takes larger-than-life portraits of ordinary families, literary luminaries and rock stars using a rare, 200-pound Polaroid Land 20×24 camera. “Surely, never in my life I thought he would do this.”

“She’s a remarkable character,” says Morris, who first encountered Dorfman 25 years ago through an ad in the local paper. He bought a session for his then-4-year-old son and was enchanted; she’s since photographed Morris and his family “20 or 40 times.”

But Morris was astounded when he first waded into her archive a few years ago. “She was pulling these Polaroids out and telling all these stories,” he says. “I thought, ‘This is a movie.’”

Dorfman grew up outside of Boston. After graduating from Tufts University in 1959, she landed a job as a secretary at Greenwich Village’s alternative Grove Press, where the “nice Jewish girl” rubbed shoulders with counterculture figures such as Allen Ginsberg.

“The first time I met Allen he asked me where ‘the can’ was, and I had no idea what he meant,” she says. He would become a lifelong friend, and Dorfman’s portraits of him are among her most tender and moving.

Dorfman got her first camera after she moved back to Massachusetts in the early 1960s, selling her photos of famous acquaintances such as Anaïs Nin and Joni Mitchell for $2 a pop out of a shopping cart in Harvard Square. Bob Dylan’s official photographer got so jealous of the intimate snaps Dorfman took backstage during his Rolling Thunder Revue, he banished her from the premises.

“Dylan loves my photos,” Dorfman says with a laugh.

In 1980, Dorfman — who is married with an adult son — found her true medium, the large-format Polaroid Land camera, which instantly produces colorful, gigantic pictures and which fits her personality. She lets her clients choose one photo per session, and she keeps the outtakes, or “B-sides.”

“In a way, Elsa is a B-side photographer,” says Morris. “She is a woman photographer who never got her due … But she worked in a commercial venue producing great art in the process.”

Film is no longer made for that model, and Dorfman estimates she only has about two years left before her stockpile runs out. But she’ll continue making her sunny photos till that day.

“It’s a dying art, and Elsa is one of its great practitioners,” says Morris. “In many ways, she’s a role model for me.”